Male threaded member, female threaded member, fastener

Abstract

To provide a male threaded member that can improve wear resistance when connecting hot water pipes. [Solution] A first connecting member 14 connected to a pumping pipe 11 in which a water channel 12 for pumping water from underground to the surface is formed, the first connecting member 14 being made of a polymer material and having a first hollow portion 51 formed through it in the axial direction S1, with one end connected to the end of the pumping pipe 11 such that the first hollow portion 51 communicates with the channel 12, and a second hollow portion 52 formed through it in the axial direction S1, with one end connected to the other end of the first connecting member 14 such that the second hollow portion 52 communicates with the first hollow portion 51, and a male threaded portion 18 being made of metal and having a thread 19 formed on part or all of the outer surface of the portion that does not overlap with the first connecting member 14 in the axial direction S1.

Description

Technical Field

[0001] The present invention relates to a male threaded member, a female threaded member, and a fastener.

Background Art

[0002] A hot water lifting pipe is a pipe in which a flow path for hot spring water pumped from underground to the ground is formed inside. Also, a plurality of hot water lifting pipes are connected in series and extend from the ground to underground, and the lowermost hot water lifting pipe is connected to a pump provided underground to suck up the hot spring water.

[0003] In order to connect the hot water lifting pipes to each other, a male threaded member or / and a female threaded member is provided at the end of each hot water lifting pipe. For the materials of the hot water lifting pipe, the male threaded member, and the female threaded member, conventionally, FRP (Fiber Reinforced Plastics) has often been used as described in Patent Document 1 below.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The male threaded member and the female threaded member made of FRP have high corrosion resistance, but there is a problem in that the wear resistance when detaching the male threaded member of one hot water lifting pipe and the female threaded member of the other hot water lifting pipe is low.

[0006] In view of the above problems, an object of the present invention is to provide a male threaded member, a female threaded member, and a fastener that improve the wear resistance when detaching the hot water lifting pipes while maintaining the corrosion resistance.

Means for Solving the Problems

[0007] To solve the above problems, the male threaded member according to the first aspect of the present invention is a connecting member connected to a pumping pipe in which a water channel for pumping water from underground to the surface is formed inside, and comprises a connecting member made of a polymer material, in which a first hollow portion is formed to penetrate in the axial direction, and one end is connected to the end of the pumping pipe so as to communicate with the first hollow portion and the water channel, and a male threaded portion made of metal, in which a second hollow portion is formed to penetrate in the axial direction, and one end is connected to the other end of the connecting member so as to communicate with the first hollow portion, and threads are formed on the outer surface of part or all of the portion that does not overlap with the connecting member in the axial direction.

[0008] Furthermore, in a second aspect of the present invention, the portion of the male screw portion that overlaps with the connecting member in the axial direction has an outer diameter that changes in the axial direction and is an insertion portion that is inserted into a part of the first hollow portion, and the part of the first hollow portion is shaped to accommodate the insertion portion.

[0009] Furthermore, in a third aspect of the present invention, the outer circumferential surface of the insertion portion and the inner circumferential surface of a part of the first hollow portion are polygonal in radial cross-sectional view.

[0010] Furthermore, the female threaded side member according to the fourth aspect of the present invention is a female threaded portion connected to a pumping pipe in which a water channel for pumping water from underground to the surface is formed, wherein a third hollow portion is formed to penetrate through in the axial direction, and one end is connected to the end of the pumping pipe such that the third hollow portion communicates with the channel, and a screw hole is formed in part or all of the portion of the third hollow portion that does not overlap with the channel in the axial direction, comprising a female threaded portion made of metal and a connecting member made of a polymer material provided to cover the outer circumferential surface of the female threaded portion.

[0011] Furthermore, in a fifth aspect of the present invention, one or more protrusions are formed on the inner circumferential surface of the connecting member, and one or more recesses that engage with the protrusions are formed on the outer circumferential surface of the female screw portion.

[0012] Furthermore, in the sixth aspect of the present invention, the inner circumferential surface of the connecting member and the outer circumferential surface of the female screw portion are polygonal in radial cross-sectional view.

[0013] Furthermore, the female screw side member according to the seventh aspect of the present invention comprises a female screw portion made of metal, formed with a third hollow portion passing through it in the axial direction, and a screw hole formed in part or all of the third hollow portion; a connecting member that is connected to a pumping pipe in which a water passage for water pumped up from underground to the surface is formed, and is provided so as to cover the outer circumferential surface of the female screw portion and is cylindrical in shape and is longer in the axial direction toward one end than the female screw portion; and a reduced diameter portion provided on the inner circumference of the cylindrical portion so as to be in contact with one end of the female screw portion, with a fourth hollow portion formed by passing through it in the axial direction and communicating with the third hollow portion, and the fourth hollow portion further communicating with the water passage, and is connected to the end of the pumping pipe, and is made of a polymer material.

[0014] Furthermore, in the eighth aspect of the present invention, one or more protrusions are formed on the inner circumferential surface of the cylindrical portion other than the reduced diameter portion, and one or more recesses that fit into the protrusions are formed on the outer circumferential surface of the female screw portion.

[0015] Furthermore, in the ninth aspect of the present invention, the convex portion and the concave portion extend along the axial direction.

[0016] Furthermore, in the tenth aspect of the present invention, the convex portion and the concave portion extend along the circumferential direction.

[0017] Furthermore, the fastener according to the eleventh aspect of the present invention comprises the male screw-side member and the female screw-side member, and the second hollow portion and the third hollow portion are connected by screwing the screw thread and the screw hole together. [Effects of the Invention]

[0018] The male threaded member, female threaded member, and fastener according to the present invention make it possible to improve wear resistance when attaching and detaching lifting pipes while maintaining corrosion resistance.

Brief Description of the Drawings

[0019] [Figure 1] It is an axial cross-sectional view of the male screw side member according to the first embodiment of the present invention. [Figure 2] It is a cross-sectional view taken along the line II-II (radial cross-sectional view) of FIG. 1. [Figure 3] It is an axial cross-sectional view of the female screw side member according to the first embodiment of the present invention. [Figure 4] It is a cross-sectional view taken along the line IV-IV (radial cross-sectional view) of FIG. 3. [Figure 5] It is an axial cross-sectional view of the fastener (formed by screwing together the male screw side member and the female screw side member) according to the first embodiment of the present invention. [Figure 6] It is a perspective view of the male screw side member according to the second embodiment of the present invention. [Figure 7] It is a perspective view of the female screw side member according to the first embodiment of the present invention. [Figure 8] It is a radial cross-sectional view corresponding to the cross-sectional view taken along the line II-II of FIG. 1 of the male screw side member according to the third embodiment of the present invention. [Figure 9] It is a radial cross-sectional view corresponding to the cross-sectional view taken along the line IV-IV of FIG. 3 of the female screw side member according to the fourth embodiment of the present invention. [Figure 10] It is an axial cross-sectional view of the female screw side member according to the fifth embodiment of the present invention. [Figure 11] It is a cross-sectional view taken along the line XI-XI (radial cross-sectional view) of FIG. 10. [Figure 12] It is an axial cross-sectional view of the female screw side member according to the sixth embodiment of the present invention. [Figure 13] It is a cross-sectional view taken along the line XIII-XIII (radial cross-sectional view) of FIG. 12.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. For ease of understanding of the description, the same reference numerals are appropriately assigned to the same components in each drawing, and duplicate descriptions are appropriately omitted.

[0021] ==First Embodiment== The first embodiment of the present invention will be described below.

[0022] <<Structure of the male screw side component>> Figure 1 is an axial cross-sectional view of the male screw-side member 2 according to the first embodiment of the present invention.

[0023] The male threaded member 2 shown in Figure 1 is connected to the hot water pipe 11 and mainly comprises a first connecting member 14 and a male threaded portion 18.

[0024] The first connecting member 14 is made of FRP. A first hollow portion 51 is formed through the first connecting member 14 along the axial direction S1. Furthermore, one end of the first connecting member 14 is connected to the end of the pumping pipe 11, and the first hollow portion 51 is configured to communicate with the flow path 12 of the pumping pipe 11.

[0025] The pumping pipe 11 is a pipe in which a channel 12 for water (hot spring water) to be pumped from underground to the surface is formed. The pumping pipe 11 is made of, for example, FRP. In addition, a thread 13 is formed on the outer surface of the end of the pumping pipe 11. Preferably, the end of the pumping pipe 11 in which the thread 13 is formed has a tapered shape such that the outer diameter decreases towards the tip.

[0026] Furthermore, a screw hole 15 is formed at one end of the first connecting member 14 within the first hollow portion 51, with a shape corresponding to the threads 13 of the molten metal pipe 11. The screw hole 15 is formed by threading (forming screw threads) on a portion of the inner circumferential surface of the first hollow portion 51. As a result, when an operator rotates the first connecting member 14 so that the threads 13 are screwed into the screw hole 15, one end of the first connecting member 14 is connected to the end of the molten metal pipe 11. This connection may be removable, or it may be made non-removable by increasing the fastening force of the screwed portion between the threads 13 and the screw hole 15, or by applying adhesive to the screwed portion.

[0027] Furthermore, a portion 16 of the first hollow portion 51 of the first connecting member 14 is shaped to accommodate the insertion portion 20, which will be described later (a shape corresponding to the insertion portion 20).

[0028] The male threaded portion 18 is made of a metal such as iron or SUS (stainless steel). A second hollow portion 52 is formed to penetrate the male threaded portion 18 along the axial direction S1. Furthermore, one end of the male threaded portion 18 is connected to the other end of the first connecting member 14, and the second hollow portion 52 is configured to communicate with the first hollow portion 51.

[0029] Furthermore, threads 19 are formed on the outer circumferential surface of the male threaded portion 18 in the portion that does not overlap with the first connecting member 14 in the axial direction S1. In addition, an insertion portion 20 is formed in the portion of the male threaded portion 18 that overlaps with the first connecting member 14 in the axial direction S1, and the outer diameter changes in the axial direction S1. Note that the change in the outer diameter in the axial direction S1 may be a change in a constant direction (such as shrinking in one direction in the axial direction S1), or it may be a change that repeatedly shrinks and expands. Figure 1 shows the latter shape. The insertion portion 20 is inserted into a part 16 of the second hollow portion 52.

[0030] Figure 2 is a section view (radial section view) of line II-II in Figure 1. As shown in Figure 2, the outer circumferential surface of the insertion portion 20 is formed in a polygonal shape in a radial cross-sectional view. Preferably, this polygon is a hexagon, pentagon, quadrilateral, or triangle. Furthermore, the inner circumferential surface of a portion 16 of the first hollow portion 51 of the first connecting member 14 is also polygonal in accordance with this.

[0031] <<Configuration of the female thread side component>> Figure 3 is an axial cross-sectional view of the female screw-side member 3 according to the first embodiment of the present invention.

[0032] The female threaded member 3 shown in Figure 3 is connected to the hot water pipe 21 and mainly comprises a female threaded portion 26 and a second connecting member 24.

[0033] The female threaded portion 26 is made of a metal such as iron or SUS (stainless steel). A third hollow portion 61 is formed to penetrate the female threaded portion 26 along the axial direction S2. Furthermore, one end of the female threaded portion 26 is connected to the end of the molten metal lifting pipe 21, and the third hollow portion 61 is configured to communicate with the flow path 22 of the molten metal lifting pipe 21.

[0034] The pumping pipe 21 is a pipe in which a water channel 22 for water (hot spring water) pumped from underground to the surface is formed. The pumping pipe 21 is made of, for example, FRP. In addition, a thread 23 is formed on the outer surface of the end of the pumping pipe 21. Preferably, the end of the pumping pipe 21 in which the thread 23 is formed has a tapered shape such that the outer diameter decreases towards the tip.

[0035] Furthermore, a screw hole 25 is formed at one end of the female screw portion 26 of the third hollow portion 61, with a shape corresponding to the threads 23 of the molten metal lifting pipe 21. The screw hole 25 is formed by threading (forming screw threads) on the inner surface of a part of the third hollow portion 61. As a result, when an operator rotates the female screw portion 26 so that the threads 23 are screwed into the screw hole 25, one end of the female screw portion 26 is connected to the end of the molten metal lifting pipe 21.

[0036] Furthermore, a screw hole 28 is formed in part or all of the third hollow portion 61 that does not overlap with the flow path 22 in the axial direction S2. The screw hole 28 has a shape corresponding to the threads 19 of the male screw-side member 2. The inner circumferential surface of part or all of the screw hole 28 is threaded (threads are formed). This allows an operator to connect the male screw-side member 2 and the female screw-side member 3 by rotating the male screw-side member 2 or the female screw-side member 3 so that the threads 19 are screwed into the screw hole 28.

[0037] The second connecting member 24 is made of FRP. The second connecting member 24 is provided so as to cover the outer surface of the female thread portion 26, and its thickness is, for example, several millimeters. One end of the second connecting member 24 is fixed to the pumping pipe 21. As described above, with one end of the female thread portion 26 connected to the end of the pumping pipe 21, the second connecting member 24 can be fixed to the pumping pipe 21 by coating (such as by dipping) the second connecting member 24.

[0038] Furthermore, a protrusion 29 extending along the axial direction S2 is formed on the inner circumferential surface of the second connecting member 24, and a recess 30 (groove) extending along the axial direction S2 is formed on the outer circumferential surface of the female thread portion 26.

[0039] Figure 4 is a cross-sectional view (radial cross-section) of Figure 3, taken along the line IV-IV. As shown in Figure 4, the inner and outer surfaces of the second connecting member 24 and the female threaded portion 26, respectively, have a circular or nearly circular shape when viewed in a radial cross-sectional view.

[0040] Furthermore, four protrusions 29 are formed on the inner circumferential surface of the second connecting member 24 at equal intervals in the circumferential direction, and four recesses 30 are formed on the outer circumferential surface of the female screw portion 26 at equal intervals in the circumferential direction. Each recess 30 fits into each protrusion 29. In addition, it is sufficient to have one or more protrusions 29 and recesses 30. Preferably, there are 8 to 36. Furthermore, if there are multiple protrusions 29 and recesses 30, they may be formed at uneven intervals rather than equal intervals in the circumferential direction. Furthermore, although Figure 4 shows the radial cross-sectional shapes of the protrusions 29 and recesses 30 as semicircular, these shapes may be other shapes, such as a square or a triangle with corners pointing inward (preferably towards the axial direction S2 in Figure 3). Also, the protrusions 29 may be formed on the inner circumferential surface of the female screw portion 26, and the recesses 30 may be formed on the second connecting member 24.

[0041] ≪Overall Structure≫ Figure 5 is an axial cross-sectional view of the fastener 1 according to the first embodiment of the present invention. As shown in Figure 5, the fastener 1 comprises a male screw-side member 2 and a female screw-side member 3. Furthermore, when the hollow portion 61 is designated as the third hollow portion, the fastener 1 is configured such that the second hollow portion 52 and the third hollow portion 61 are connected by screwing the screw threads 19 and the screw hole 28 together. Specifically, the second hollow portion 52 and a portion of the third hollow portion 61 are connected in such a way that they overlap. In other words, the hot water pipe 11 and the hot water pipe 21 are connected in series via the fastener 1. This allows the water (hot spring water) flowing through the channel 12 of the hot water pipe 11 to flow into the channel 22 of the hot water pipe 21 (conversely, water may also flow from channel 22 to channel 22).

[0042] <Effects> The male threaded side member 2 according to the first embodiment is a first connecting member 14 connected to a pumping pipe 11 in which a water passage 12 for pumping water from underground to the surface is formed, and comprises a first connecting member 14 made of FRP with a first hollow portion 51 formed to penetrate in the axial direction S1, and one end of which is connected to the end of the pumping pipe 11 so that the first hollow portion 51 communicates with the passage 12, and a male threaded portion 18 made of metal with a second hollow portion 52 formed to penetrate in the axial direction S1, and one end of which is connected to the other end of the first connecting member 14 so that the second hollow portion 52 communicates with the first hollow portion 51, and threads 19 are formed on part or all of the outer circumferential surface of the part that does not overlap with the first connecting member 14 in the axial direction S1. As a result, the male threaded member 2 has a metal male threaded portion 18 on which the threads 19 are formed, and its outer circumference is surrounded by a first connecting member 14 made of FRP. Therefore, when the threads 19 are screwed into the screw hole 28, the metal male threaded portion 18 is less likely to be exposed to the outside. The metal threads 19 have high wear resistance when attaching and detaching from the screw hole 28, and the first connecting member 14 made of FRP has high corrosion resistance to the external environment. Therefore, the male threaded member 2 can improve wear resistance when attaching and detaching the pumping pipes while maintaining corrosion resistance. Furthermore, the male screw-side member 2 has a male screw portion 18 on which the screw threads 19 are formed, which is made of metal, and its outer circumference is surrounded by a first connecting member 14 made of FRP, so that the hot spring water can be kept warm when it flows through the first hollow portion 51.

[0043] Furthermore, in the male screw-side member 2 according to the first embodiment, the portion of the male screw portion 18 that overlaps with the first connecting member 14 in the axial direction S1 has an outer diameter that changes in the axial direction S1 and is an insertion portion 20 that is inserted into a part 16 of the first hollow portion 51, and the part 16 of the first hollow portion 51 has a shape into which the insertion portion 20 is fitted. This allows the male screw-side member 2 to prevent the male screw portion 18 from falling out of the first connecting member 14 (by providing resistance to axial movement).

[0044] In the male screw-side member 2 according to the first embodiment, the outer circumferential surface of the insertion portion 20 and the inner circumferential surface of a part 16 of the first hollow portion 51 are polygonal in radial cross-sectional view. For example, if the outer circumferential surface of the insertion portion 20 and the inner circumferential surface of a part 16 of the first hollow portion 51 are perfectly circular in a radial cross-sectional view, the insertion portion 20 may spin freely against the first connecting member 14 when inserting or removing the screw threads 19 from the screw hole 28. The male screw-side member 2 can prevent this free spinning because its cross-sectional view is polygonal.

[0045] The female threaded side member 3 according to the first embodiment of the present invention is a female threaded portion 26 connected to a pumping pipe 21 in which a water passage 22 for pumping water from underground to the surface is formed, and a hollow portion 61 is formed to penetrate in the axial direction S2, and one end is connected to the end of the pumping pipe 21 such that the hollow portion 61 communicates with the passage 22, and a screw hole 28 is formed in part or all of the portion of the hollow portion 61 that does not overlap with the passage 22 in the axial direction S2, and comprises a female threaded portion 26 made of metal and a second connecting member 24 made of FRP that is provided to cover the outer circumferential surface of the female threaded portion 26. As a result, the female threaded member 3 has a female threaded portion 26 in which the screw hole 28 is formed, which is made of metal, and its outer circumference is surrounded by a second connecting member 24 made of FRP. Therefore, when the screw threads 19 are screwed into the screw hole 28, the metal female threaded portion 26 is less likely to be exposed to the outside. The metal screw hole 28 has high wear resistance when attaching and detaching with the screw threads 19, and the second connecting member 24 made of FRP has high corrosion resistance to the external environment. Therefore, the female threaded member 3 can improve wear resistance when attaching and detaching the pumping pipes while maintaining corrosion resistance. Furthermore, the female screw-side member 3 has a female screw portion 26 in which the screw hole 28 is formed, which is made of metal, and its outer circumference is surrounded by a second connecting member 24 made of FRP, so that the hot spring water can be kept warm when it flows through the third hollow portion 61.

[0046] In the first embodiment of the present invention, the female threaded member 3 has one or more protrusions 29 formed on the inner circumferential surface of the second connecting member 24, and one or more recesses 30 that fit into the protrusions 29 are formed on the outer circumferential surface of the female threaded portion 26. For example, if the outer circumferential surface of the female thread portion 26 and the inner circumferential surface of the second connecting member 24 are perfectly circular in a radial cross-sectional view, the female thread portion 26 may slip relative to the second connecting member 24 when attaching or detaching the screw thread 19 to the screw hole 28. In the female thread side member 3 according to the first embodiment of the present invention, a convex portion 29 is formed on the inner circumferential surface of the second connecting member 24, and a concave portion 30 is formed on the outer circumferential surface of the female thread portion 26, thereby preventing such slippage.

[0047] The fastener 1 according to the first embodiment of the present invention comprises a male screw-side member 2 and a female screw-side member 3, and when the hollow portion 61 is designated as the third hollow portion 61, the second hollow portion 52 and the third hollow portion 61 are connected by screwing the screw threads 19 and the screw hole 28 together. The male threaded member 2 has a metal male threaded portion 18 on which the threads 19 are formed, and its outer circumference is surrounded by a first connecting member 14 made of FRP. Therefore, when the threads 19 are screwed into the screw hole 28, the metal male threaded portion 18 is less likely to be exposed to the outside. The metal threads 19 have high wear resistance when attaching and detaching from the screw hole, and the first connecting member 14 made of FRP has high corrosion resistance to the external environment. As a result, the male threaded member 2 can improve wear resistance when attaching and detaching the hot water pipes while maintaining corrosion resistance. Furthermore, in the female threaded member 3, the female threaded portion 26 in which the screw hole 28 is formed is made of metal, and its outer circumference is surrounded by a second connecting member 24 made of FRP. Therefore, when the screw threads 19 are screwed into the screw hole 28, the metal female threaded portion 26 is less likely to be exposed to the outside. The metal screw hole 28 has high wear resistance when attaching and detaching with the screw threads 19, and the second connecting member 24 made of FRP has high corrosion resistance to the external environment. Thus, the female threaded member can improve wear resistance when attaching and detaching the pumping pipes while maintaining corrosion resistance. Therefore, the fastener 1 can improve wear resistance when attaching and detaching the hot water pipes while maintaining corrosion resistance. Furthermore, the male screw-side member 2 has a metal male screw portion 18 in which the screw threads 19 are formed, and its outer circumference is surrounded by a first connecting member 14 made of FRP, so that the hot spring water can be kept warm when it flows through the first hollow portion 51. Also, the female screw-side member 3 has a metal female screw portion 26 in which the screw hole 28 is formed, and its outer circumference is surrounded by a second connecting member 24 made of FRP, so that the hot spring water can be kept warm when it flows through the third hollow portion 61 (and the second hollow portion 52).

[0048] ==Second Embodiment== <<Structure>> The following describes the second embodiment, focusing on the differences from the first embodiment. Figure 6 is a perspective view of the male threaded member 2A according to the second embodiment of the present invention. Note that Figure 6 shows the state in which the hot water supply pipe 11 is not inserted into the male threaded member 2A.

[0049] In the first embodiment, the male threaded side member 2 comprises a first connecting member 14 made of FRP and a male threaded portion 18 made of metal, which is separate from the first connecting member 14. In contrast, the male threaded side member 2A in the second embodiment comprises a first connecting member 34 corresponding to the first connecting member 14 and a male threaded portion 38 that is integrated with the first connecting member 34 and corresponds to the male threaded portion 18.

[0050] The first connecting member 34 and the male threaded portion 38 are made of metal. This metal may be SUS or a metal with higher corrosion resistance than SUS (such as titanium).

[0051] Furthermore, Figure 7 is a perspective view of the female threaded member 3A according to the second embodiment of the present invention. Note that in Figure 6, the state in which the hot water pipe 21 is not inserted into the female threaded member 3A is also shown.

[0052] In the first embodiment, the female threaded member 3 comprises a female threaded portion 26 made of metal and a second connecting member 24 made of FRP, which is separate from the female threaded portion 26. In contrast, the female threaded member 3A in the second embodiment comprises a female threaded portion 46 corresponding to the female threaded portion 26.

[0053] The female thread portion 46 shall be made of metal. This metal may be SUS or a metal with higher corrosion resistance than SUS (such as titanium).

[0054] <Effects> In the male threaded member 2A, female threaded member 3A, and fastener (male threaded member 2A and female threaded member 3A) according to the second embodiment, corrosion resistance is reduced compared to the first embodiment, but manufacturing is simplified.

[0055] ==Third Embodiment== <<Structure>> The following section will describe the third embodiment, focusing on the differences from the first embodiment. Figure 8 is a radial cross-sectional view of the male screw-side member 2B according to the third embodiment of the present invention, corresponding to the II-II cross-sectional view in Figure 1.

[0056] In the male screw-side member 2 according to the first embodiment shown in Figure 2, the radial cross-sectional shapes of the outer circumferential surface of the insertion portion 20 and the inner circumferential surface of the first connecting member 14 are hexagonal (polygonal). In contrast, in the male screw-side member 2B of the third embodiment shown in Figure 8, the outer circumferential surface of the insertion portion 20A, which corresponds to the insertion portion 20 of the first embodiment, has a shape in which a recess is formed at a predetermined position that is a perfect circle or nearly a perfect circle. Furthermore, in the male screw-side member 2B, the inner circumferential surface of the first connecting member 14A, which corresponds to the first connecting member 14 according to the first embodiment, also has a shape in which a protrusion is formed at a predetermined position that is a perfect circle or nearly perfect circle, and which engages with the recess (a shape corresponding to the outer circumferential surface of the insertion portion 20A). Note that the protrusion and recess shown in Figure 8 extend in the axial direction (axial direction S1 in Figure 1).

[0057] Although Figure 8 shows a state in which four protrusions and four recesses are formed, the male screw-side member 2 is not limited to this; it is sufficient if one or more of these protrusions and recesses are formed thereon. Furthermore, if there are multiple protrusions and recesses, they do not need to be formed at equal or uneven intervals in the circumferential direction. Furthermore, although Figure 8 shows that the radial cross-sectional shapes of the convex and concave portions are rectangular, these shapes may be other shapes, such as a semicircle or a triangle with corners pointing inward (preferably towards the axial direction S1 in Figure 1). Alternatively, the protrusion may be formed on the outer circumferential surface of the insertion portion 20, and the recess may be formed on the inner circumferential surface of the first connecting member 14A.

[0058] <Effects> In the male screw-side member 2B according to the third embodiment, the presence of a convex portion and a concave portion prevents the insertion portion 20A from spinning freely against the first connecting member 14A when the screw threads 19 are inserted into and removed from the screw hole 28.

[0059] ==Fourth Embodiment== <<Structure>> The following section will describe the fourth embodiment, focusing on the differences from the first embodiment. Figure 9 is a radial cross-sectional view of the female screw-side member 3B according to the fourth embodiment of the present invention, corresponding to the cross-sectional view taken along line IV-IV in Figure 3.

[0060] In the female threaded member 3 according to the first embodiment shown in Figure 4, the radial cross-sectional shapes of the inner and outer circumferential surfaces of the second connecting member 24 and the female threaded portion 26 are circular or approximately circular, and a convex portion 29 and a concave portion 30 are formed. In contrast, in the female screw-side member 3B of the fourth embodiment shown in Figure 9, the shape of the radial cross-sectional view of the inner circumferential surface of the second connecting member 24A, which corresponds to the second connecting member 24 of the first embodiment, is octagonal. Furthermore, in the female thread side member 3B, the shape of the outer circumferential surface of the female thread portion 26A, which corresponds to the female thread portion 26 according to the first embodiment, in a radial cross-sectional view is octagonal (the shape corresponding to the inner circumferential surface of the second connecting member 24A). In addition, the female screw-side member 3B according to the fourth embodiment does not have a protrusion 29 and a recess 30 formed thereon.

[0061] Furthermore, the shape of the female screw-side member 3B is not limited to an octagon, but can be any polygon. Preferably, the shape is an octagon to a 36-sided polygon.

[0062] <Effects> In the female screw-side member 3B according to the fourth embodiment, the shape of the inner circumferential surface of the second connecting member 24A in a radial cross-sectional view, and the shape of the outer circumferential surface of the female screw portion 26A in a radial cross-sectional view are polygonal. Therefore, when attaching or detaching the screw threads 19 to and from the screw hole 28, it is possible to prevent the female screw portion 26 from spinning freely against the second connecting member 24. In particular, by making the above shape 36-sided or less, the slippage can be prevented more reliably. Also, in a radial cross-sectional view, the smaller the interior angles of the polygon on the outer surface of the female screw portion 26A, the more the force applied by each corner of the outer surface to the second connecting member 24A is concentrated, reducing the strength of the second connecting member 24A. Therefore, in the fourth embodiment, the strength of the second connecting member 24A is ensured by making the above shape octagonal or greater.

[0063] ==Fifth Embodiment== <<Structure>> In the following, the fifth embodiment of the present invention will be described, focusing on the differences from the first embodiment, and similar configurations will be omitted from the explanation as appropriate.

[0064] Figure 10 is an axial cross-sectional view of the female screw-side member 3C according to the fifth embodiment. Figure 11 is a cross-sectional view (radial cross-section) of section XI-XI in Figure 10.

[0065] The female threaded member 3C shown in Figures 10 and 11 is connected to the hot water pipe 21 and mainly comprises a female threaded portion 26C and a second connecting member 24C.

[0066] The female threaded portion 26C is formed by a third hollow portion 61C passing through it in the axial direction S5, and a threaded hole 28 is formed in part or all of the third hollow portion 61C, and is made of metal.

[0067] The second connecting member 24C is a connecting member that connects to a pumping pipe 21 in which a water channel 22 for pumping water from underground to the surface is formed, and is made of FRP, with a cylindrical portion 40 and a reduced diameter portion 41 as its main parts.

[0068] The cylindrical portion 40 is provided so as to cover the outer circumferential surface of the female thread portion 26C, and is cylindrical in shape that is longer at one end than the female thread portion 26C in the axial direction S5.

[0069] The reduced diameter portion 41 is a thick-walled portion in the second connecting member 24C where the inner diameter is narrowed. The reduced diameter portion 41 is provided on the inner circumference of the cylindrical portion 40 (integrally with the cylindrical portion 40) so as to be in contact with (closely attached to) one end of the female thread portion 26C. Furthermore, the reduced diameter portion 41 is formed by a fourth hollow portion 62C passing through it in the axial direction S5, communicating with the third hollow portion 61C. The reduced diameter portion 41 is then connected to the end of the pumping pipe 21 such that the fourth hollow portion 62C further communicates with the flow path 22.

[0070] Furthermore, a threaded hole 25C is formed in part or all of the fourth hollow portion 62C. The threaded hole 25C has a shape corresponding to the threads 23 at the end of the pumping pipe 21, and its inner surface is threaded (threads are formed). The threaded hole 25C is then screwed into the threads 23. In addition, one end of the second connecting member 24C may be fixed to the pumping pipe 21 by coating or the like when the threaded hole 25C is screwed into the threads 23.

[0071] Furthermore, it is preferable that the inner surface of the third hollow portion 61C and the inner surface of the fourth hollow portion 62C are flush with each other or smoothly connected.

[0072] Furthermore, one or more protrusions 29C are formed on the inner circumferential surface of the cylindrical portion 40, excluding the reduced-diameter portion 41. The protrusions 29C extend along the axial direction S5. Preferably, four protrusions 29C are formed in a row in the circumferential direction. Note that the axial direction S5 refers to the axial direction of the cylindrical portion 40, but as shown in Figure 10, the axial directions of the reduced-diameter portion 41, the molten metal lifting pipe 21, and the female threaded portion 26C are also in the same direction. Similarly, the circumferential direction here also refers to the circumferential direction of the cylindrical portion 40, but the axial directions of the reduced-diameter portion 41, the molten metal lifting pipe 21, and the female threaded portion 26C are also in the same direction.

[0073] Furthermore, one or more recesses 30C that engage with the protrusions 29C are formed on the outer circumferential surface of the female thread portion. The recesses 30C extend along the axial direction S5. Preferably, four recesses 30C are formed arranged in the circumferential direction. Note that the axial direction S5 refers to the axial direction of the female thread portion 26C, but as already explained, the axial directions of the cylindrical portion 40, the reduced diameter portion 41, and the pumping pipe 21 are in the same direction. Similarly, the circumferential direction here also refers to the circumferential direction of the female thread portion 26C, but the axial directions of the cylindrical portion 40, the reduced diameter portion 41, and the pumping pipe 21 are in the same direction.

[0074] <Effects> In the female screw-side member 3C according to the fifth embodiment, the metal portion can be reduced and the FRP can be increased compared to the female screw-side member 3 according to the first embodiment, thus making it lighter.

[0075] ==Sixth Implementation Method== <<Structure>> In the following, the sixth embodiment will be described, focusing on the differences from the fifth embodiment, and explanations of similar configurations will be omitted as appropriate.

[0076] Figure 12 is an axial cross-sectional view of the female screw-side member 3D according to the sixth embodiment of the present invention. Figure 13 is a cross-sectional view (radial cross-section) of the line XIII-XIII in Figure 12.

[0077] The female screw-side member 3D according to the sixth embodiment, shown in Figures 12 and 13, differs from the female screw-side member 3C according to the fifth embodiment in that it has a protrusion 29D and a recess 30D instead of the protrusion 29C and recess 30C shown in Figure 10. Furthermore, the 24D, screw hole 25D, female screw portion 26D, third hollow portion 61D, fourth hollow portion 62D, and axial direction S6 of the female screw-side member 3D correspond to the second connecting member 24C, screw hole 25C, female screw portion 26C, third hollow portion 61C, and fourth hollow portion 62C of the female screw-side member 3C, respectively.

[0078] As shown in Figure 13, the protrusion 29D extends along the circumferential direction. Also, as shown in Figure 12, preferably two protrusions 29D are formed side-by-side in the axial direction S6. Note that the circumferential direction here refers to the female thread portion 26D. of It refers to the circumferential direction. , tube The circumferential directions of the shaped portion 40, the reduced diameter portion 41, and the pumping pipe 21 are also the same. Similarly, the axial direction S6 also refers to the axial direction of the female thread portion 26D, as shown in Figure 12, Cylindrical part 40, Reduced diameter part 41, hot water pipe 2 1 The axis direction is also the same.

[0079] As shown in Figure 13, the recess 30D extends along the circumferential direction. Also, as shown in Figure 12, preferably two recesses 30D are formed side by side in the axial direction S6. Note that the circumferential direction here refers to the circumferential direction of the cylindrical portion 40, but as already explained, the female thread portion 26D, the reduced diameter portion 41, and the pumping pipe 21 Zhou The direction is also the same. Similarly, the axial direction S6 also refers to the axial direction of the cylindrical portion 40, but as already explained, the female screw portion 26 D , shrinkage The axial direction of the diameter portion 41 and the axial direction of the pumping pipe 21 are the same.

[0080] ==Torture== It should be noted that the present invention is not limited to the embodiments described above. That is, any design modifications made to the above-described examples by those skilled in the art are also included within the scope of the present invention, as long as they retain the features of the present invention. Furthermore, the elements of the above embodiments and the following modifications can be combined to the extent that it is technically possible, and any combination thereof is also included within the scope of the present invention, as long as it retains the features of the present invention.

[0081] For example, the structure of each connecting member 14, 24, 14A, 24A, 24C, and 24D described in each embodiment may be changed from a single layer to a multilayer structure, for example, by using carbon fiber reinforced resin for the inner layer and glass fiber reinforced resin for the outer layer. This makes it possible to improve resistance to external environmental factors (heat, moisture, corrosion) and resistance to mechanical stress during screw insertion and removal in a balanced manner.

[0082] Furthermore, the metals described in each embodiment may be changed from stainless steel or titanium alloys to cobalt-chromium alloy (Co-Cr), which has excellent wear resistance. This allows for even higher wear resistance in applications where screws are frequently attached and detached.

[0083] Furthermore, the shape of the screw thread 19 and screw hole 28 described in each embodiment may be changed from a normal triangular screw to a "trapezoidal screw" or a "square screw". This improves the ability to prevent screw loosening under axial loads and vibrations, making it suitable for deep underground installation of pumping pipes.

[0084] Furthermore, the outer circumferential surface of the second connecting members 24, 24A, and 24C described in each embodiment may be provided with one or more ribs extending in the axial direction or in the circumferential direction. This strengthens the bending rigidity of the structure, protecting the connection points from deflection and distortion caused by ground movement and the weight of the pumping pipes.

[0085] Furthermore, the screw threads 19 and screw holes 28 described in each embodiment may be coated with a molybdenum-based or fluorine-based self-lubricating coating. This reduces the coefficient of friction during repeated attachment and detachment operations, thereby suppressing wear progression and stabilizing the screw-in torque.

[0086] Furthermore, in each embodiment, the first connecting members 14, 14A, 34 and the second connecting members 24, 24A, 24C, 24D are made of FRP, a type of polymer material. However, similar effects can be achieved even if these are made of other polymer materials such as rigid PVC (thermoplastic plastic).

[0087] Furthermore, a silane coupling layer or a thermoplastic elastomer layer may be interposed between the male thread portion and the first connecting member, and between the female thread portion and the second connecting member, as described in each embodiment. This prevents delamination caused by the difference in thermal expansion coefficients between metal and FRP (polymer material), and also alleviates local stress generated during screw insertion and removal. In particular, it enables the long-term maintenance of joint reliability when used in high-temperature and high-humidity environments such as hot spring water.

[0088] Furthermore, the surface of the threads in the male screw portion and the surface (inner circumferential surface) of the screw hole in the female screw portion may be subjected to nitriding, borization, or laser cladding treatment as described in each embodiment. This significantly increases the surface hardness of the screw portion, suppressing wear and galling even in applications with frequent attachment and detachment. Furthermore, the reduction in wear dust generation prevents foreign matter from contaminating hot spring water, offering hygienic advantages. [Explanation of symbols]

[0089] 1: Fasteners 2,2A,2B: Male thread side member 3, 3A, 3B, 3C: Female thread side member 11,21: Fried hot water pipe 12,22: Flow channel 13,19: Screw thread 14, 14A, 34: First connecting member 15, 25, 25C, 25D, 28: Screw holes 16: Part of (the first hollow section) 18,38: Male threaded section 20: Insertion part 24, 24A, 24C, 24D: Second connecting member 26, 26A, 26C, 26D, 46: Female thread section 29, 29C, 29D: Convex part 30, 30C, 30D: Recessed 40: Cylindrical part 41: Reduced diameter section 51: First hollow section 52: Second hollow section 61, 61C, 61D: Third hollow section 62C, 62D: Fourth hollow section

Claims

1. A first connecting member connected to a first pumping pipe having a water channel formed inside which water is pumped from underground to the surface, wherein a first hollow portion is formed to penetrate through it in the axial direction, and one end is connected to the end of the first pumping pipe such that the first hollow portion communicates with the water channel, and the first connecting member is made of a polymer material, A male threaded portion made of metal is formed, having a second hollow portion that penetrates through it in the axial direction, with one end connected to the other end of the first connecting member such that the second hollow portion communicates with the first hollow portion, and having threads formed on part or all of the outer surface of the portion that does not overlap with the first connecting member in the axial direction. A male screw-side member having, A third hollow portion is formed through the axial direction, and a screw hole is formed in part or all of the third hollow portion, and a female screw portion made of metal is formed, A second connecting member connected to a second pumping pipe having a water channel formed inside through which water is pumped from underground to the surface, comprising: a cylindrical portion provided so as to cover the outer surface of the female thread portion and being cylindrical in shape and longer in the axial direction than the female thread portion toward one end; and a reduced-diameter portion provided on the inner circumference of the cylindrical portion so as to be in contact with one end of the female thread portion, thereby narrowing its inner diameter and forming a fourth hollow portion that penetrates axially and communicates with the third hollow portion, and the fourth hollow portion further communicates with the water channel, and is connected to the end of the second pumping pipe, the second connecting member made of a polymer material, A female threaded side member having, Equipped with, By screwing the aforementioned threads and the aforementioned screw hole together, the second hollow portion and the third hollow portion are connected. Fasteners.

2. One or more protrusions are formed on the inner circumferential surface of the cylindrical portion, in a portion other than the reduced diameter portion. One or more recesses are formed on the outer circumferential surface of the female screw portion, which engage with the convex portion. The fastener according to claim 1.

3. The convex portion and the concave portion extend along the axial direction. The fastener according to claim 2.

4. The aforementioned protrusions and recesses extend along the circumferential direction. The fastener according to claim 2.

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